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Stimulation of metazooplankton by photochemically modified dissolved organic matter
Author(s) -
Daniel Cesar,
Granéli Wilhelm,
Kritzberg Emma S.,
Anesio Alexandre M.
Publication year - 2006
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2006.51.1.0101
Subject(s) - microcosm , dissolved organic carbon , eutrophication , environmental chemistry , heterotroph , organic matter , biology , ecology , chemistry , bacteria , nutrient , genetics
We examined the response of bacteria and proto‐ and metazooplankton to photomodified dissolved organic matter (DOM). Sterile filtered water from a eutrophic and a humic lake, that was either exposed to artificial ultraviolet (UV) radiation or kept dark, was added to semicontinuous laboratory microcosms that lasted for 7 weeks. Bacterial production responded positively to photochemical modification of DOM regardless of lake type. Final heterotrophic biomass (bacteria1proto1metazooplankton) was 47 ± 5 and 37 ± 5 µg carbon (C) L −1 in microcosms with UVexposed and unaltered eutrophic water DOM and 15 ± 4 and 11 ± 2 µg C L −1 in microcosms with UV‐exposed and unaltered humic water DOM, respectively. For the eutrophic water, there were no significant differences in proto‐ or metazooplankton biomasses between microcosms receiving UV‐exposed or nonexposed DOM. Differences between eutrophic water microcosms were not significant when flagellates, ciliates, cladocerans, and copepods were examined separately. In microcosms with UV‐exposed humic water, biomasses of heterotrophic flagellates, rotifers, nauplii, and cladocerans were higher than in those with nonexposed DOM. Higher final metazooplankton biomass following addition of UV‐exposed humic water indicates that photochemically modified DOM can be effectively transferred through the microbial loop.